Security ToolsFree
HMAC Generator
Generate HMAC (Hash-based Message Authentication Code) signatures using SHA-256. Enter your message and secret key to produce a tamper-proof signature that verifies both message integrity and authenticity. Uses the Web Crypto API — entirely in-browser.
Updated June 2026
- 1Enter your message and secret key
- 2Choose a hash algorithm
- 3Copy the generated HMAC
How to use HMAC Generator
- 1
Enter your message and secret key
Type or paste the message and the shared secret key.
- 2
Choose a hash algorithm
Pick SHA-256 or another supported algorithm.
- 3
Copy the generated HMAC
Grab the resulting signature for verification.
Frequently asked questions
Everything you need to know about hmac generator.
HMAC verifies that a message was not tampered with in transit and was sent by someone who knows the secret key. It is widely used for API authentication, webhook signature verification, and data integrity checks.
HMAC-SHA256, using the browser's Web Crypto API. This is the most widely used HMAC variant and the standard for API authentication (e.g., AWS signatures, Stripe webhooks).
A plain SHA-256 hash has no secret key — anyone can verify or create it. HMAC-SHA256 requires knowing the secret key to produce or verify the signature, making it suitable for authentication.
Yes. The Web Crypto API handles all HMAC computation locally. Your message and secret key are never sent to any server.
Compute the HMAC of the received message with the same secret key. If the computed HMAC matches the received HMAC exactly, the message is authentic and unmodified.
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